This is what I'm doing :-
a. I asked the priest to give Divine Luck and that was successful.
(before the fight start)
b. Then went to fight (the rogue hidden as the leader)
c. Then as our rogue can see the mushroom men the fight is started.
d. But as the mushroom men cannot see beyond a certain limit they
don't do anything.
e. Then when out turn comes then I move one of the heroes to just
behind the rogue.
f. Unwittingly the mushroom men come and I get the Window of opportunity.
g. Sometimes it just gets stuck at the window of opportunity or after
the opportunity has ended and it's the mushroom men's turn. Either the
mushroom men is killed or sometimes it shows that one of the heroes
turn it is but nothing happens when I try to move him or anything.
I just hope this doesn't confuse the issue more.